4-(2-Fluoro-4-halo-5-substituted phenyl)urazols, and their production and use

ABSTRACT

A condensed phenylurazol of the formula:  &lt;IMAGE&gt;  wherein X is a chlorine atom or a bromine atom, Y and Z are each an oxygen atom or a sulfur atom and R is a C1-C3 alkyl group, an allyl group or a propargyl group and n is an integer of 4 or 5, which is useful as a herbicide.

The present invention relates to 4-(2-fluro-4-halo-5-substitutedphenyl)urazols bearing a condensed hexahydropyridazine orhexahydrodiazepine ring (hereinafter referred to as "the condensedphenylurazol (s)"), and their production and use.

The said condensed phenylurazols are representable by the formula:##STR2## wherein X is a chlorine atom or a bromine atom, Y and Z areeach an oxygen atom or a sulfur atom, R is a C₁ -C₃ alkyl group, anallyl group or a propargyl group and n is an integer of 4 or 5.

It is known that some 4-phenylurazols exhibit a herbicidal activity. Forinstance, U. S. Pat. No. 4,249,934, Japanese Patent Publication(unexamined) No. 44587/1978, etc. disclose that2-(4-chlorophenyl-5,6,7,8,-tetrahydro-1H-[1,2,4]triazolo[1,2-a]pyridazine-1,3(2H)-dione,2-(4-chloro-2-flurophenyl)-5,6,7,8-tetrahydro-1H-[1,2,4]-triazolo[1,2-a]pyridazine-1,3(2H)-dione,2-(4-chlorophenyl)-1H, 5H-[1,2,4]triazolo[1,2-a][1,2]diazepin-1,3(2H)-dione, etc. show a herbicidal activity.However, their herbicidal effect is not always satisfactory.

It has been found that the condensed phenylurazols (I) show a strongherbicidal activity against a wide variety of weeds includingGraminaceous weeds, Cyperaceae weeds and broad-leaved weeds at smalldoses and do not produce any material phytotoxicity on variousagricultural crops (e.g. corn, soybean, cotton, wheat). Examples ofGraminaceous weeds against which the condensed phenylurazols (I) show aherbicidal activity are barnyardgrass (Echinochloa crus-galli), greenfoxtial (Setaria viridis), large crabgrass (Digitaria sanguinalis),Johnsongrass (Sorghum halepense), wild oat (Avena fatua), black grass(Alopecurus myosuroides), goosegrass (Eleusine indica), annual bluegrass(Poa annua), bermudagrass (Cynodon dactylon), quackgrass (Agropyronrepens), etc. Examples of broad-leaved weeds are tall mornigglory(Ipomoea purpurea), velvetleaf (Abutilon theophrasti), sicklepod (Cassiaobtusifolia), wild sunflower (Helianthus annus), cocklebur (Xanthiumpensylvanicum), wild mustard (Brassica kaber), common chickweed(Stellaria media), common purslane (Portulaca oleracea), jimsonweed(Datura stramonium), hemp sesbania (Sesbania exaltata), sun spurge(Euphorbia helioscopia), black nightshade (Solanum nigrum), prickly sida(Sida spinosa), common ragweed (Ambrosia artemisiifolia), smartweed sp.(Polygonum sp.), redroot pigweed (Amaranthus retroflexus), bedstraw(Galium aparine), pineappleweed (Matricaria spp.), birdseye speedwell(Veronica persica), wild buckwheat (Polygonum convolvulus), beggarticks(Bidens spp.), common lambsquarters (Chenopodium album), bindweed(Calystegia japonica), monochoria (Monochoria vaginalis), Dopatriumjunceum, waterwort (Elatine triandra), false pimpernel (Linderniaprocumbens), toothcup (Rotala indica), arrowhead (Sagittaria pygmaea),etc. Examples of Cyperaceae weeds are nutsedge sp. (Cyperus microiria),purple nutsedge (Cyperus rotundus), yellow nutsedge (Cyperusesculentus), hardstem bulrush (Scirpus juncoides), nutsedge (Cyperusserotinus), water chestnut (Eleocharis kuroguwai), slender spikerush(Eleocharis acicularis), etc. Accordingly, the condensed phenylurazols(I) can be used as herbicides applicable to paddy fields as well as toan agricultural plowed field. They are also useful as herbicides to beemployed for a crop field, orchard, tea garden, mulberry field, rubberplantation, forest, lawn, pasture, non-agricultural field, etc.

The condensed phenylurazols (I) can be produced by various procedures,among which typical examples are shown below:

PROCEDURE A

The condensed phenylurazols of the formula (I) wherein at least one of Yand Z is an oxygen atom can be produced by reacting a phenylurazol ofthe formula: ##STR3## wherein X, Y, Z and R are each as defined abovebut at least one of Y and Z is an oxygen atom with a dihaloalkane of theformula:

    A--(CH.sub.2).sub.n --A'                                   (III)

wherein A and A' are each a halogen atom (e.g. chlorine, bromine) and nis as defined above, usually in an inert solvent (e.g.dimethylformamide, dimethylsulfoxide, acetonitrile, ethylene glycolmenomethyl ether, tetrahydrofuran, diethyl ether) at a temperature of-80° to 200° C.

Preferably, the phenylurazol (II) is previously metallized, and themetallized phenylurazol is subjected to reaction with the dihaloalkane(III). The metallization may be achieved by treatment of thephenylurazol (II) with a metallizing agent (e.g. sodium alkoxide, sodiumhydride, n-butyl lithium) in an inert solvent (e.g. methanol, ethanol,diethyl ether, tetrahydrofuran) at a temperature of -8° to 160° C. Thethus produced metallized phenylurazol canbe subjected to reaction withthe dihaloalkane (III) as above with or without its isolation from thereaction mixture.

PROCEDURE B

The condensed phenylurazols of the formula (I) wherein Z is an oxygenatom and n is an integer of 4 can be produced by treatment of a urea ofthe formula: ##STR4## wherein R' is a lower alkyl group (e.g. methyl,ethyl, n-propyl, isopropyl) and X, Y and R are each as defined abovewith a base (e.g. sodium methoxide, sodium hydroxide, potassiumhydroxide) in an inert solvent (e.g. water, toluene, benzene, methanol,ethanol) at a temperature of 0° to 200° C.

PROCEDURE C

The condensed phenylurazols of the formula (I) wherein Z is an oxygenatom and n is an integer of 4 can be produced by reacting a urea of theformula: ##STR5## wherein X, R and Y are each as defined above withphosgene in an inert solvent (e.g. toluene, tetrahydrofuran,1,4-dioxane) at a temperature of from 0° C. to the boiling temperatureof the solvent. When desired, a base (e.g. triethylamine, pyridine,diethylaniline) may be present in the reaction system.

PROCEDURE D

The condensed phenylurzols of the formula (I) wherein Z is a sulfur atomand n is an integer of 4 can be produced by reacting a urea of theformula: ##STR6## wherein X, R and Y are each as defined above withcarbon disulfide in an inert solvent (e.g. methanol, ethanol,tetrahydrofuran) in the presence of a base such as an alkali metalhydroxide (e.g. sodium hydroxide, potassium hydroxide) or a tertiaryamine (e.g. pyridine, triethylamine).

PROCEDURE E

The condensed phenylurazols of the formula (I) wherein Y and Z are eacha sulfur atom can be produced by reacting the corresponding condensedphenylurazol of the formula (I) wherein Y and Z are each an oxygen atomwith phosphorus pentasulfide in an inert solvent (e.g. xylene, toluene,hexane) at the boiling temperature of the solvent.

The production of the starting materials is summarized in the followingscheme: ##STR7## wherein X, Y, Z, R and R' are each as defined above.

Namely, the phenol (VI) is selectively nitrated to the nitrophenol(VII), which is subjected to alkylation, alkenylation or alkynylation.The resultant nitrobenzene (VIII) is subjected to reduction, and theresulting aniline (IX) is reacted with phosgene or thiophosgene to givethe isocyanate or isothiocyanate (X), which is reacted with anN-alkoxycarbonylhexahydropyridazine to give the urea (IV). Hydrolysisand decarboxylation of the urea (IV) give the urea (V). The aboveaniline (IX) is created with a 2-alkoxycarbonylhydrazinecarbonylchloride, followed by cyclization with a base to give the phenylurazol(II). Alternatively, the phenylurazol (II) can be produced by reactingthe isocyanate or isothiocyanate (X) with an alkoxycarbonylhydrazine,followed by cyclization with a base.

Explaining the above conversions more in detail, the nitration of thephenol (VI) to the nitrophenol (VII) may be accomplished by applicationof a per se conventional nitration procedure to the former. Usually,however, the indirect nitration which consists of the following threesteps is favorable in achievement of the selective nitration at thedesired position: ##STR8## wherein X is as defined above. Thus, thephenol (VI) (Finger et. al.: J.Am.Chem.Soc., 81, 94 (1959)) is convertedinto its alkali metal salt by treatment with an aqueous solution of analkali metal hydroxide (e.g. sodium hydroxide, potassium hydroxide), andthe resulting salt is reacted with an alkyl haloformate such as methylchloroformate in water at a temperature of 0° to 10° C. The thusprepared carbonic ester (XI) is nitrated with a mixture of conc.sulfuric acid and conc. nitric acid at room temperature. Then, thenitrobenzene (XII) thus obtained is hydrolyzed with an aqueous alkalinesolution such as an aqueous sodium hydrxoide solution at a temperatureof 40° to 80° C. to give the nitrophenol (VII).

The alkylation, alkenylation or alknylation for conversion of thenitrophenol (VII) into the nitrobenzene (VIII) may be carried out bytreatment of the former with an alkali metal carbonate (e.g. potassiumcarbonate), an alkali metal hydride (e.g. sodium hydride) or an alkalimetal alkoxide (e.g. sodium methoxide) and reacting the resultant alkalimetal salt with a halide of the formula: R-Q wherein Q is a halogen atom(e.g. chlorine, bromine, iodine) and R is as defined above in a polarsolvent (e.g. water, dimethylformamide, acetonitrile, acetone,dimethylsulfoxide), usually at a temperature of 10° to 200° C.,preferably of 30° to 100° C. The use of a phase transfer catalyst suchas tetrabutylammonium bromide is favorable for smooth accomplishment ofthe reaction.

Reduction of the nitrobenzene (VIII) to the aniline (IX) may be achievedin various procedures. When, for instance, R in the compound (VIII) isC₁ -C₄ alkyl, there may be adopted a per se conventional reductionprocedure for converting a nitro group into an amino group wherein areducing agent such as sodium sulfide or iron powder or catalyticreduction is employed. One of the typical procedures comprisesintroduction of a 3 molar amount of hydrogen into a reaction systemcomprising one molar amount of the compound (VIII) and a 1/10 to 1/100molar amount of platinum dioxide at room temperature under atmosphericpressure. Another typical procedure comprises admixing an acetic acidsolution containing one molar amount of the compound (VIII) with a 5%acetic acid solution containing a 2.5 to 5.0 molar amount of iron powdersuch as reductive iron or electrolytic iron and effecting the reactionat a temperature of 80° to 100° C. When R in the compound (VIII) ispropargyl or allyl, there may be adopted reduction with iron powder. Forinstance, an acetic acid solution containing one molar amount of thecompound (VIII) may be admixed with a 5% acetic acid solution containinga 2.5 to 5.0 molar amount of iron powder such as reductive iron orelectrolytic iron at a temperature of 80° to 120° C., preferably of 90°to 110° C., for a period of 0.5 to 5 hours.

The aniline (IX) is converted into the isocyanate or isothiocyanate (X)by reacting the former with phosgene or thiophosgene in an inert solvent(e.g. toluene, benzene, ethyl acetate, tetrahydrofuran, 1,4-dioxane).

The isocyanate or isothiocyanate (X) can be converted into the urea (IV)by reacting the former with an N-alkoxycarbonylhexahydropyridazine in aninert solvent (e.g. benzene, toluene, hexane, tetrahydrofuran),preferably in the presence of an organic base (e.g. pyridine,triethylamine), at a temperature from room temperature (ca. 20° C.) tothe boiling temperature of the solvent.

Hydrolysis and decarboxylation of the urea (IV) by treatment with anaqueous alkaline solution at a temperature of 0° to 100° C. affords theurea (V).

Alternatively, the phenylurazol (II) can be produced by reacting theisocyanate or isothiocyanate (X) with an alkoxcarbonylhydrazine oralkoxythiocarbonylhydrazine in an inert solvent (e.g. toluene,chloroform, tetrahydrofuran) at a temperature of 0° to 100° C., followedby treatment of the resultant semicarbazide of the formula: ##STR9##wherein R" is an alkyl group and X, Y, Z and R are each as defined abovewith an aqueous alkaline solution such as potassium hydroxide solutionand then with a mineral acid (e.g. hydrochloric acid, sulfuric acid).

The above obtained aniline (IX) can be converted into the semicarbazide(XIII) by reacting the former with a 2-alkoxycarbonylhydrazinecarbonylchloride in an inert solvent (e.g. benzene, toluene, diethyl ether,tetrahydrofuran, dioxane) at the boiling temperature of the solvent.

The above produced condensed phenylurazols (I) and their intermediatesare, when desired, purified by a per se conventional procedure such asrecrystallization or column chromatography.

Practical and presently preferred embodiments for production of thecondensed phenylurazols (I) are shown in the following Examples.

EXAMPLE 1

To a solution of metallic sodium (0.7 g) in methanol (40 ml),4-(4-chloro-2-fluoro-5-methoxy)urazol (3.87 g) was added, and resultantmixture was concentrated under reduced pressure. A solution of1,4-dibromobutane (3.5 g) in dimethylformamide (40 ml) was addedthereto. The resulting mixture eas stirred at 100° to 110° C. for 4hours. After being allowed to cool to room temperature, water was addedto the mixture, which was then extracted with ether. The ether layer waswashed with water, dried and concentrated to give crystals. The crystalswere washed with ether to give 1.26 g of2-(4-chloro-2-fluoro-5-methoxyphenyl)-5,6,7,8-tetrahydro-1H-[1,2,4]triazolo[1,2-a]-pyridazine-1,3(2H)-dione(Compound No. 1) as colorless crystals. M.P., 131° -132° C. IR ν_(max)(cm⁻¹): 1770, 1720. δ (ppm): 1.9 (4H, m), 3.6 (4H, m), 3.85 (3H, s),6.85 (1H, d, J=6 Hz), 7.3 (1H, d, J=10 Hz).

EXAMPLE 2

To a solution of metallic sodium (0.46 g) in methanol (20 ml),2-(4-chloro-2-fluoro-5-methoxyph(2.6 g) was added, and the resultantmixture was concentrated under reduced pressure. The residue wasdissolved in dimethylformamide (20 ml), 1,5-dibromopentane (2.3 g) wasadded thereto, and the resulting mixture was stirred at 100° to 120° C.for 4 hours. After being allowed to cool, water was added to themixture, which was then extracted with ethyl acetate. The extract waswashed with a saturated sodium chloride solution, dried over anhydrousmagnesium sulfate and concentrated under reduced pressure. The residuewas purified by silica gel column chromatography and recrystallized frommethanol to give 0.42 g of2-(4-chloro-2-fluoro-5-methoxyphenyl)-1H,5H-[1,2,4]triazolo[1,2-a]-[1.2]diazepine-1,3(2H)-doine(Compound No. 3). M.P., 121.5°-123° C. Ir ν_(max) (cm⁻¹): 1750, 1680.NMR δ (ppm): 1.8 (6H, m), 3.9 (3H, s).

EXAMPLE 3

Ethyl2-[(4-chloro-2-fluoro-5-(1-methylethoxy)-phenyl)aminothioxomethyl]-3,4,5,6-tetrahydro-1(2H)-pyridazinecarboxylate(0.66 g) was dissolved in toluene (20 ml), and several drops of sodiummethoxide were added thereto, followed by heating under reflux for 3hours. Water was added to the resultant mixture, which was thenextracted with toluene. The extract was washed with a saturated sodiumchloride solution, dried and concentrated to give 0.3 g of2[4-chloro-2-fluoro-5-(1-methylethoxy)-phenyl]-5,6,7,8-tetrahydro-1H-[1,2,4]triazolo[1,2-a]-pyridazine-3-thioxo-1(2H)-one(Compound No. 15). n_(D) ²⁵ 1.5720. IR ν_(max) (cm⁻¹): 1740, 1490, 1250.δ (ppm): 1.4 (6H, d), 2.0 (4H, m), 3.65 (2H, m), 4.0 (2H, m), 4.45 (1H,m), 6.9 (1H, d).

EXAMPLE 4

2(4-Bromo-5-ethoxy-2-fluorophenyl)-1H,5H-[1.2.4]-triazolo[1,2-a][1,2]diazepine-1,3(2H)-dione(0.63 g) was dissolved in xylene (10 ml), and phosphorus pentasulfide(0.46 g) was added thereto, followed by heating under reflux for 8hours. The reaction mixture was filtered to eliminate insolublematerials, and the filtrate was concentrated under reduced pressure. Theresidue was crystallized and washed with methanol to give 0.65 g of2-(4-bromo-5-ethoxy-2-fluorophenyl)-1H,5H-[1,2,4]triazolo[1,2-a][1.2]diazepine-1,3(2H)-dithione (Compound No. 9). M.P.,173.5°-174.5° C. IR ν_(max) (cm⁻¹): 1290. δ (ppm): 1.45 (3H, t), 1.9(6H, m), 4.07 (2H, q).

Some additional examples of the condensed phenylurazol (I) produced inthe same manner as above are shown in Table 1.

                  TABLE 1                                                         ______________________________________                                         ##STR10##                                                                    Com-                                                                          pound                                                                         No.   X     Y     Z   n   R          Physical property                        ______________________________________                                        1     Cl    O     O   4   CH.sub.3   M.P. 131-132° C.                  2     Cl    S     O   4   CH.sub.3   M.P. 146-147° C.                  3     Cl    O     O   5   CH.sub.3   M.P. 121.5-123° C.                4     Cl    S     S   5   CH.sub.3   M.P. 229-231° C.                  5     Br    O     O   4   CH.sub.3   M.P. 162.5-164.5° C.              6     Cl    O     O   4   CH.sub.2 CH.sub.3                                                                        M.P. 116-117° C.                  7     Br    O     O   4   CH.sub.2 CH.sub.3                                                                        M.P. 141-143° C.                  8     Br    O     O   5   CH.sub.2 CH.sub.3                                                                        M.P. 56-58°  C.                   9     Br    S     S   5   CH.sub.2 CH.sub.3                                                                        M.P. 173.5-174.5° C.              10    Cl    O     O   4   CH.sub.2 CH.sub.2 CH.sub.3                                                               M.P. 97.5-99° C.                  11    Cl    S     S   4   CH.sub.2 CH.sub.2 CH.sub.3                                                               M.P. 181.5-182.5° C.              12    Cl    O     O   5   CH.sub.2 CH.sub.2 CH.sub.3                                                               n.sub.D.sup.22.0 1.5310                  13    Br    O     O   4   CH.sub.2 CH.sub.2 CH.sub.3                                                               M.P. 92-93° C.                    14    Cl    O     O   4   CH(CH.sub.3).sub.2                                                                       M.P. 140-142.5° C.                15    Cl    S     O   4   CH(CH.sub.3).sub.2                                                                       n.sub.D.sup.25 1.5720                    16    Cl    S     O   4   CH.sub.2 CHCH.sub.2                                                                      M.P. 58-63° C.                    17    Br    O     O   4   CH.sub.2 CHCH.sub.2                                                                      M.P. 109-111° C.                  18    Cl    S     O   4   CH.sub.2 CCH                                                                             M.P. 148-150° C.                  ______________________________________                                    

EXAMPLE 5

A solution of 2-fluoro-4-chloro-5-n-propoxyphenyl isocyanate (1.8 g) inbenzene (10 ml) was added to a toluene solution containingmethoxycarbonylhydrazine (0.71 g), and the resultant mixture was allowedto stand overnight. The precipitated crystals were collected byfiltration and dissolved in a 4M aqueous sodium hydroxide solution (10ml) under heating. To the resulting solution, conc. hydrochloric acidwas added, and the precipitated crystals were collected by filtration togive 2.6 g of 4-(4-chloro-2-fluoro-5-n-propoxyphenyl)urazol. M.P.,181°-182° C. IR ν_(max) (cm⁻¹): 3150, 1710, 1680. δ (ppm): 1.1 (3H, t),4.0 (3H, q), 7.0 (1H, d), 7.3 (1H, d).

Some examples of the phenylurazol (II) produced in the same manner asabove are shown in Table 2.

                  TABLE 2                                                         ______________________________________                                         ##STR11##                                                                    X     Y       Z      R          Physical property                             ______________________________________                                        Cl    O       O      CH.sub.3   M.P. 223-224° C.                       Cl    S       O      CH.sub.3   Glassy; IR ν.sub.max                                                       (cm.sup.-1): 3160, 1720                       Cl    O       O      CH.sub.2 CH.sub.2 CH.sub.3                                                               M.P. 181-182° C.                       Br    O       O      CH.sub.3   M.P. 229-230° C.                       Br    O       O      CH.sub.2 CH.sub.3                                                                        M.P. 215-216° C.                       Br    O       O      CH.sub.2 CH.sub.2 CH.sub.3                                                               M.P. 189-189.5° C.                     Cl    O       O      CH.sub.2 CCH                                                                             M.P. 217-217.5° C.                     ______________________________________                                    

EXAMPLE 6

4-Chloro-2-fluoro-5-(1-methylethoxy)phenyl isothiocyanate (2.8 g) wasadded to a solution of2-ethoxycarbonyl-3,4,5,6-tetrahydro-(1H,2H)-pyridazine (1.8 g) andseveral drops of triethylamine in toluene (5 ml), and the resultantmixture was stirred at 25° C. overnight. Water was added to the mixture,which was then extracted with toluene. The toluene layer was washed withwater, dried and concentrated.The residue was purified by silica gelcolumn chromatography to give 2 of ethyl2-(4-chloro-2fluoro-5-(1-methylethoxy)phenylaminothioxomethyl)-3,4,5,6-tetrahydro-1(2H)pyridazine carboxylate. n_(D) ²⁷.5 1.5534. NMR δ (ppm): 1.3 (3H, t), 1.4(6H, d), 1.8 (4H, m), 4.35 (2H, q), 7.1 (1H, d), 8.0 (1H, d), ##STR12##

Some examples of the urea (IV) produced in the same manner as above areshown in Table 3.

                  TABLE 3                                                         ______________________________________                                         ##STR13##                                                                    X    Y      R            R'      Physical property                            ______________________________________                                        Cl   S      CH.sub.3     CH.sub.2 CH.sub.3                                                                     n.sub.D.sup.24.0 1.5751                      Cl   S      CH(CH.sub.3).sub.2                                                                         CH.sub.2 CH.sub.3                                                                     n.sub.D.sup.27.5 1.5534                      Cl   O      CH.sub.2 CCH CH.sub.2 CH.sub.3                                                                     M.P. 135.5-136.5° C.                  Cl   S      CH.sub.2 CCH CH.sub.2 CH.sub.3                                                                     M.P. 105-109° C.                      Br   S      CH.sub.2 CH.sub.2 CH.sub.3                                                                 CH.sub.2 CH.sub.3                                                                     Glassy                                       Br   S      CH.sub.2 CHCH.sub.2                                                                        CH.sub.2 CH.sub.3                                                                     M.P. 80-86° C.                        Br   O      CH.sub.2 CHCH.sub.2                                                                        CH.sub.2 CH.sub.3                                                                     M.P. 77-80° C.                        Cl   O      CH.sub.2 CH.sub.2 CH.sub.3                                                                 CH.sub.2 CH.sub.3                                                                     n.sub.D.sup.25 1.5313                        ______________________________________                                    

EXAMPLE 7

A solution of ethyl2-(4-chloro-2-fluoro-5-(-methylethoxy)phenylaminothioxometyl)-3,4,5,6-tetrahydro1(2H)pyridazinecarboxylate(0.8 g) in a 5% ethanolic potassium hydroxide solution (10 ml) washeated under reflux for 3 hours. After being allowed to cool to roomtemperature, ethanol was removed under reduced pressure. The residue wasdissolved in ether, washed with water, dried over anhydrous magnesiumsulfate and concentrated to give 0.3 g of2-(4-chloro-2-fluoro-5-(1-methylethoxy)phenylaminothioxomethyl)-3,4,5,6-tetrahydro-(1H,2H)-pyridazine.M.P., 113°-114.5° C. δ (ppm): 1.35 (6H, d), 1.7 (4H, m), 2.95 (2H, m),3.45 (1H, t), 4.2 (2H, m), 4.4 (1H, m), 6.95 (1H, d), 8.25 (1H, d), 9.85(1H, m).

Some examples of the urea (V) produced in the same manner as above areshown in Table 4.

                  TABLE 4                                                         ______________________________________                                         ##STR14##                                                                    X     Y        R             Physical property                                ______________________________________                                        Cl    S        CH(CH.sub.3).sub.2                                                                          M.P. 113-114.5° C.                        Cl    O        CH.sub.2 CH.sub.2 CH.sub.3                                                                  M.P. 120-122.5° C.                        Cl    O        CH.sub.2 CCH  M.P. 89.5-91.5° C.                        Cl    S        CH.sub.2 CCH  M.P. 96.5-99° C.                          Cl    O        CH.sub.2 CHCH.sub.2                                                                         M.P. 91-95° C.                            Br    O        CH.sub.2 CHCH.sub.2                                                                         M.P. 80-86° C.                            ______________________________________                                    

EXAMPLE 8

A solution of 4-chloro-2-fluoro-5-isopropoxy-aniline (30 g) in toluene(100 ml) was added to a 1 M phosgene/toluene solution (500 ml) at roomtemperature (ca. 20° C.), followed by heating under reflux. The mixturewas concentrated under reduced pressure, and the residue was distilledto give 26 g of 4-chloro-2-fluoro-5-isopropoxy-phenyl isocyanate as paleyellow crystals. M.P., 36°-37° C. B.P., 90°-91° C./3 mmHg.

IR ν_(max) (cm⁻¹): 2240.

Some examples of the isocyanate or isothiocyanate (X) produced in thesame manner as above are shown in Table 5.

                  TABLE 5                                                         ______________________________________                                         ##STR15##                                                                    X   Y     R            Physical property                                      ______________________________________                                        Cl  O     CH.sub.3     M.P. 42-44.5° C.                                Cl  O     n-C.sub.3 H.sub.7                                                                          M.P. 43-44° C.                                  Cl  O     iso-C.sub.3 H.sub.7                                                                        M.P. 36-37° C.                                  Br  O     C.sub.2 H.sub.5                                                                            M.P. 35-36.5° C.                                Cl  O     CH.sub.2CHCH.sub.2                                                                         B.P. 107° C./3 mmHg; n.sub.D.sup.16 1.5481      Cl  O     CHCCH.sub.2  M.P. 61.5-62.5° C.                              Cl  S     CH.sub.3     M.P. 79-80° C.                                  Cl  S     CHCCH.sub.2  M.P. 105-109° C.                                Cl  S     CH.sub.2CHCH.sub.2                                                                         n.sub.D.sup.24 1.6228                                  Br  S     CHCCH.sub.2  M.P. 71-74° C.                                  Br  S     CH.sub.2CHCH.sub.2                                                                         n.sub.D.sup.24 1.6421                                  ______________________________________                                    

EXAMPLE 9

A mixture of 4-chloro-2-fluoro-5-isopropoxy-nitrobenzene (13.5 g) andplatinum dioxide (0.4 g) in ethanol (300 ml) was subjected to catalyticreduction with hydrogen at room temperature (ca. 20° C.) underatmospheric pressure, whereby a designed amount of hydrogen wasabsorbed. The resultant mixture was filtered to remove insolublematerials, and the filtrate was concentrated. The residue was subjectedto purification by silica gel chromatography to give 5.6 g of4-chloro-2-fluoro-5-isopropoxyphenylaniline. n_(D) ²⁴.5 1.5360.

(CDCl₃) δ (ppm): 1.3 (6H, d, J=6Hz), 3.7 (2H, m, J=1.5Hz), 4.35 (1H, q,J=6 Hz), 6.45 (1H, d, J=7 Hz), 7.1 (1H, d, J=10 Hz).

IR ν_(max) (cm⁻¹): 3450, 3550.

EXAMPLE 10

A suspension of electrolytic iron powder (3.5 g) in a 5% aqueous aceticacid solution (5 ml) was heated to 90° C., and a solution of4-chloro-2-fluoro-5-(2-propynyloxy)-nitrobenzene (5.7 g) in acetic acid(40 ml) was dropwise added thereto at the same temperature. Theresultant mixture was stirred at 90°-105° C. for 1 hour and allowed tocool to room temperature. Water (200 ml) was added thereto. Insolublematerials were filtered off, and the filtrate was neutralized, followedby extraction with ethyl acetate. The extract was dried over anhydrousmagnesium sulfate and concentrated. The residue was washed withpetroleum ether and carbon tetrachloride to give 3.6 g of4-chloro-2-fluoro-5-(2-propynyloxy)aniline. M.P. 61.0°-61.5° C.

(CDCl₃) δ (ppm): 2.5 (1H, t, J=2 Hz), 3.4-4.2 (2H, m, J=16 Hz), 4.15(2H, d, J=2 Hz), 6.5 (1H, d, J=8Hz), 6.95 (1H, d, J=10 Hz).

IR ν_(max) (cm⁻¹): 3460, 3360, 3280, 2100.

Some examples of the aniline (IX) produced in the same manner as aboveare shown in Table 6.

                  TABLE 6                                                         ______________________________________                                         ##STR16##                                                                    X        R               Physical property                                    ______________________________________                                        Cl       C.sub.2 H.sub.5 n.sub.D.sup.24.5 1.5503                              Br       C.sub.2 H.sub.5 n.sub.D.sup.25.0 1.5680                              Cl       n-C.sub.3 H.sub.7                                                                             n.sub.D.sup.24.5 1.5386                              Br       n-C.sub.3 H.sub.7                                                                             n.sub.D.sup.26.0 1.5618                              Cl       iso-C.sub.3 H.sub.7                                                                           n.sub.D.sup.24.5 1.5360                              Br       iso-C.sub.3 H.sub.7                                                                           n.sub.D.sup.25.0 1.5547                              Cl       CH.sub.2CHCH.sub.2                                                                            n.sub.D.sup.19 1.5598                                Cl       CHCCH.sub.2     M.P. 61.0-61.5° C.                            Cl                                                                                      ##STR17##      M.P. 67.0-68° C.                              ______________________________________                                    

EXAMPLE 11

To a solution of 2-chloro-4-fluoro-5-nitrophenol (19.1 g) inacetonitrile (100 ml), there was added anhydrous potassium carbonate (8g). After stirring at room temperature (ca. 20° C.) for several minutes,isopropyl iodide (25 g) was added thereto, and the resultant mixture washeated unde reflux for 3 hours. After being allowed to cool to roomtemperature (ca. 20° C.), water was added thereto, and the reactionmixture was extracted with ether. The ether extract was washed with a 5% aqueous sodium hydroxide solution and water in order, dried overanhydrous magnesium sulfate and filtered. The filtrate was concentratedunder reduced pressure, and the residue was recrystallized from ethanolto give 13.5 g of 4-chloro-2-fluoro-5-isopropoxynitrobenzene. M.P.,61.3°-62.4° C.

NMR (CDCl₃) δ (ppm): 1.42 (6H, d, J=7 Hz), 4.3-4.8 (1H, m), 7.28 (1H, d,J=10 Hz), 7.48 (1H, d, J=6 Hz).

Some examples of the nitrobenzene (VIII) produced in the same manner asabove are shown in Table 7.

                  TABLE 7                                                         ______________________________________                                         ##STR18##                                                                    X        R                Physical property                                   ______________________________________                                        Cl       CH.sub.3         M.P. 67.5-69.8° C.                           Br       CH.sub.3         M.P. 72.2° C.                                Cl       CH.sub.2 CH.sub.3                                                                              M.P. 47-48° C.                               Br       CH.sub.2 CH.sub.3                                                                              M.P. 46-46.5° C.                             Cl       CH.sub.2 CH.sub.2 CH.sub.3                                                                     M.P. 46-47° C.                               Br       CH.sub.2 CH.sub.2 CH.sub.3                                                                     M.P. 46.8-47.4° C.                           Cl       CH(CH.sub.3).sub.2                                                                             M.P. 61.3-62.4° C.                           Br       CH(CH.sub.3).sub.2                                                                             M.P. 65.5-66.5° C.                           Cl       CH(CH.sub.3)CH.sub.2 CH.sub.3                                                                  M.P. 59.6-60.6° C.                           Cl       CH.sub.2 CHCH.sub.2                                                                            n.sub.D.sup.17.0 1.5601                             Cl                                                                                      ##STR19##       M.P. 41.0-41.5° C.                           Cl       CH.sub.2 CCH     M.P. 88-89° C.                               Cl                                                                                      ##STR20##       M.P. 87-88° C.                               ______________________________________                                    

EXAMPLE 12

2-Chloro-4-fluorophenol (83.4 g) was added to a solution of sodiumhydroxide (27.7 g) in water (450 ml), and methyl chloroformate (69.2 g)was dropwise added thereto at a temperature below 10° C. Precipitatedcrystals were collected by filtration and washed with water to givemethyl (2-chloro-4-fluorophenyl) formate (134.8 g). M.P., 69°-71° C.

Methyl (2-chloro-4-fluorophenyl)formate (134.8 g) obtained above wassuspended in conc. sulfuric acid (50 ml). To the suspension, a mixtureof conc. sulfuric acid (50 ml) and conc. nitric acid (50 ml) was addedat about 30° C., and the mixture was stirred at this temperature for 1hour. The reaction mixture was poured into ice water, and precipitatedcrystals were collected and washed with water to give methyl(2-chloro-4-fluoro-5-nitrophenyl)formate (143 g). M.P., 50°-55° C.

The product obtained as above was combined with sodium hydroxide (27 g)and water (300 ml), and the resultant mixture was refluxed for 4 hours.Precipitated insoluble materials were filtered using a celite, and thefiltrate was acidified with conc. hydrochloric acid. Precipitatedcrystals were collected by filtration and washed with water to obtain76.3 g of 2-chloro-4-fluoro-5-nitrophenol. M.P., 106°-107° C.

NMR (CDCl₃, D₆ -DMSO) δ (ppm): 7.25 (1H, d, J=10 Hz), 7.64 (1H, d, J=6Hz).

IR ν_(max) ^(nujol) (cm⁻¹): 3370.

EXAMPLE 13

To a solution of 2-bromo-4-fluorohenol (28 g) in a solution of sodiumhydroxide (7 g) in water (100 ml), methyl chloroformate was dropwiseadded thereto at a temperature below 10° C. The produced crystals werecollected by filtration and washed with water to give methyl2-bromo-4-fluorophenylformate (41 g). M.P., 80.7° C.

The above product was suspended in conc. sulfuric acid (13 ml), amixture of conc. sulfuric acid (13 ml) and conc. nitric acid (13 ml) wasdropwise added thereto at about 30° C., and the resultant mixture ofstirred for 30 minutes. The reaction mixture was poured into ice water.The produced crystals were collected by filtration and washed with waterto give methyl 2-bromo-4-fluoro-5-nitroformate (38.3 g) as yellowcrystals. M.P., 63.5°-64.5° C.

The thus obtained product was admixed with sodium hydroxide (6.2 g) andwater (100 ml) and heated under reflux for 3 hour. The insolublematerials were eliminated by filtration, and the filtrate was acidifiedwith hydrochloric acid. The precipitated crystals were collected byfiltration and washed with water to give 25 g of2-bromo-4-fluoro-5-nitrophenol. M.P., 126°-127° C.

NMR (CDCl₃, D₆ -DMSO) δ (ppm): 7.42 (1H, d, J=10 Hz), 7.65 (1H, d, J=6Hz).

IR ν_(max) ^(nujol) (cm⁻¹): 3450.

In the practical usage of the condensed phenylurazols (I), they may beapplied as such or in any composition form such as emulsifiableconcentrates, wettable powders, suspensions, granules or fine granules.

The concentration of the active ingredient in such composition form isusually within a range of 0.1 to 90% by weight, preferably of 1 to 80%by weight.

For formulation of those compositions, a solid or liquid carrier ordiluent may be used. As the solid carrier or diluent, there may beemployed mineral powders (e.g. kaolin clay, bentonite, talc,diatomaceous earth, sericite, synthetic hydrated silicon dioxide). Asthe liquid carrier of diluent, there may be employed aromatichydrocarbons (e.g. xylene, methylnaphthalene), ketones (e.g.cyclohexanone, isophorone), chlorobenzene, dimethylformamide,cellosolve, ethylene glycol, water, etc.

A surface active agent used for emulsification, dispersion or spreadingmay be any of the non-ionic, anionic, cationic and amphoteric type ofagents. Examples of the surface active agent include polyoxyethylenealkyl ethers, polyoxyethylene alkylaryl ethers, polyoxyethylene fattyacid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fattyacid esters, oxyethyleneoxypropylene polymers, polyoxyethylene alkylphosphates, fatty acid salts, alkyl sulfates, alkyl sulfonates,alkylaryl sulfonates, alkyl phosphates, polyoxyethylene alkyl sulfates,quaternary ammonium salts and the like. If necessary, gelatin, casein,sodium alginate, starch, agar, polyvinyl alcohol, ligninsulfonates,isopropyl acid phosphate, alginates of the like may be used as anauxiliary agent.

Practical embodiments of the herbicidal composition according to theinvention are illustratively shown in the following examples whereinpart(s) and % are by weight. The compounds number of the activeingredient corresponds to the one in Table 1.

FORMULATION EXAMPLE 1

Eighty parts of Compound No. 10, 3 parts of alkylsulfate, 2 parts ofligninsulfonate and 15 parts of synthetic hydrated silicon dioxide arewell mixed while being powdered to obtain a wettable powder.

FORMULATION EXAMPLE 2

Twenty parts of Compound No. 14, 10 parts of polyoxyethylene alkylarylether, 50 parts of cyclohexanone and 20 parts of xylene are well mixedwhile being powdered to obtain an emulsifiable concentrate.

FORMULATION EXAMPLE 3

0.1 Part of Compound No. 10, 1 part of synthetic hydrated silicondioxide, 35 parts of bentonite and 63. 9 parts of kaolin clay are wellmixed while being powdered. The mixture is then kneaded with water,granulated and dried to obtain granules.

FORMULATION EXAMPLE 4

Three parts of Compound No. 1, 0.3 part of isopropyl acid phosphate,66.7 parts of kaolin clay and 30 parts of talc are well mixed whilebeing powdered to obtain a dust.

FORMULATION EXAMPLE 5

Eighty parts of Compound No. 3, 5 parts of polyoxyethylene alkylarylether and 15 parts of synthetic hydrated silicon dioxide are well mixedwhile being powdered to obtain a wettable powder.

FORMULATION EXAMPLE 6

Ten parts of Compound No. 10, 7 parts of polyoxyethylene alkylarylether, 3 parts of alkylarylsulfate and 80 parts of cyclohexanone arewell mixed while being powdered to obtain an emulsifiable concentrate.

FORMULATION EXAMPLE 7

One part of Compound No. 9,1 part of synthetic hydrated silicon dioxide,5 parts of ligninsulfonate and 93 parts of kaolin clay are well mixedwhile being powdered. The mixture is then kneaded with water, granulatedand dried to obtain granules.

FORMULATION EXAMPLE 8

Three parts of Compound No. 3, 0.5 part of isopropyl acid phosphate,66.5 parts of kaolin clay and 30 parts of talc are well mixed whilebeing powdered to obtain a dust.

FORMULATION EXAMPLE 9

Twenty parts of Compound No. 9 is mixed with 60 parts of an aqueoussolution containing 3% polyoxyethylene sorbitan monooleate andpulverized until the particle size of the active ingredient becomes lessthan 3 microns. Twenty parts of an aqueous solution containing 3% ofsodium alginate as a dispersing agent are incorporated therein to obtaina suspension.

The dosage rate of the condensed phenylurazols (I) may vary dependingupon the application mode such as pre-emergence treatment orpost-emergence treatment, etc. Generally, however, the dosage rate isfrom 0.1 to 50 grams, preferably from 0.2 to 30 grams, of the activeingredient per are. Besides, the condensed phenylurazols (I) of theinvention may be used together with other herbicides to improve theiractvity as herbicides, and in some cases, a synergistic effect can beexpected.

The application of the condensed phenylurazols (I) as herbicides will beillustratively shown in the following Examples wherein the phytotoxicityto crop plants and the herbicidal activity on weeds were evaluated asfollows: the aerial parts of the test plants were cut off and weighed(fresh weight); the percentage of the fresh weight of the treated plantto that of the untreated plant was calculated with the latter freshweight taken as 100; and the phytotoxicity and the herbicidal activitywere evaluated by the standard given in the table below.

    ______________________________________                                                   Fresh weight                                                       Rating     (percentage to untreated plot) (%)                                 value      Herbicidal activity                                                                         Phytotoxicity                                        ______________________________________                                        0          61-           100                                                  1          41-60         90-99                                                2          21-40         80-89                                                3          11-20         60-79                                                4           1-10         40-59                                                5          0              0-39                                                ______________________________________                                    

The following compounds were used in the Examples for comparison:

    ______________________________________                                        Com-                                                                          pound                                                                         No.   Structure              Remarks                                          ______________________________________                                        (a)                                                                                  ##STR21##             U.S. Pat. No. 4,249,934                          (b)                                                                                  ##STR22##             Japanese Patent Publn. (un- examined) No.                                     44587/78                                         (c)                                                                                  ##STR23##             U.S. Pat. No. 4,249,934                          (d)                                                                                  ##STR24##             Commercially available herbicide known as                                     "Alachlor"                                       (e)                                                                                  ##STR25##             Commercially available herbicide known as                                     "Atrazine"                                       (f)                                                                                  ##STR26##             Commercially available herbicide known as                                     "Ioxynil"                                        (g)                                                                                  ##STR27##             Commercially available herbicide known as                                     "Chlor- methoxynil"                              ______________________________________                                    

TEST EXAMPLE 1

Plastic beakers (diameter, 10 cm; height, 10 cm) were filled with uplandfield soil, and the seeds of barnyardgrass, wild oat, tall morninggloryand velvetleaf and the seeds of soybean, cotton and corn were separatelysowed in the beakers. A designed amount of the test compound formulatedinto an emulsifiable concentrate according to Formulation Example 2 or 6and dispersed in water was sprayed over the top by means of a small handsprayer at a spray volume of 5 liters per are. After the spraying, thetest plants were grown for 20 days in the greenhouse, and herbicidalactivity and phytotoxicity were examined. The results are shown in Table8.

                                      TABLE 8                                     __________________________________________________________________________    Dosage                                                                        (weight of  Herbicidal activity                                                     active in-                                                                          Barn-  Tall                                                       Compound                                                                            gredient,                                                                           yard-                                                                             Wild                                                                             morning-                                                                           Velvet-                                                                            Phytotoxicity                                    No.   g/are)                                                                              grass                                                                             oat                                                                              glory                                                                              leaf Soybean                                                                            Cotton                                                                            Corn                                    __________________________________________________________________________    1     5     5   5  5    5    --   --  --                                            2.5   5   5  5    5    1    --  1                                       2     5     5   5  5    5    --   --  --                                            2.5   5   5  5    5    --   --  --                                      3     5     5   5  5    5    1    --  --                                            2.5   5   5  5    5    0    --  --                                      4     5     5   5  4    5    0    --  --                                      6     5     5   5  5    5    --   --  --                                            2.5   5   5  5    5    1    1   --                                      8     5     5   5  5    5    1    --  --                                            2.5   5   5  4    5    0    --  --                                      9     5     5   4  --   5    0    --  --                                      10    5     5   5  5    5    --   --  --                                            2.5   5   5  5    5    0    0   --                                      12    5     5   5  5    5    1    1   --                                            2.5   5   4  4    5    1    0   --                                      14    5     5   5  5    5    --   --  --                                            2.5   5   4  5    5    2    --  --                                      16    5     5   5  5    5    --   --  --                                            2.5   5   4  5    5    --   --  --                                      17    5     5   5  5    5    --   --  --                                            2.5   4   4  5    5    --   --  --                                      18    5     5   5  5    5    --   --  --                                            2.5   5   5  5    5    --   --  --                                      (a)   5     1   0  0    3    --   --  --                                            2.5   0   0  0    1    0    1   0                                       (b)   5     3   1  3    5    --   --  --                                            2.5   1   0  2    3    2    3   1                                       (c)   5     1   1  0    4    --   --  --                                            2.5   0   0  0    1    0    0   --                                      __________________________________________________________________________

TEST EXAMPLE 2

In plastic pots (diameter, 10 cm; height, 10 cm) filled with uplandfield soil, the tubers of purple nutsedge were transplanted andcultivated in a greenhouse for 4 weeks. Separately, the seeds ofbarnyardgrass, wild oat, wild mustard and velvetleaf were sowed in thesimilar pots and grown for 2 weeks in the greenhouse. A designed amountof the test compound formulated in an emulsifiable concentrate accordingto Formulation Example 2 or 6 and dispersed in water with a spreadingagent was sprayed to the foliage of the test plants by means of a smallhand sprayer at a spray volume of 5 liters per are. After the spraying,the test plants were further grown for 3 weeks in the greenhouse, andthe herbicidal activity was examined. The results are shown in Table 9.

Among the test plants, purple nutsedge was further grown for 2 weeks inthe greenhouse, and the number of revived sprouts in the treated plotwas compared with that in the untreated plot. Evaluation was made on thefollowing criteria: A, no revival; B, 1 to 10% revival; C, 11-50%revival; D, more thatn 51% revival. The results are also shown in Table9.

                  TABLE 9                                                         ______________________________________                                        Dosage                                                                        (weight of  Herbicidal activity                                                                              Prevention                                     Com-  active in-                                                                              Barn-        Wild        of revival                           pound gredient, yard-   Wild mus- Velvet-                                                                              Purple                               No.   g/are)    grass   oat  tard leaf   nutsedge                             ______________________________________                                        1     5         4       5    5    5      A                                          1.25      3       3    4    5      --                                   2     5         4       5    5    5      --                                         1.25      3       3    5    5      --                                   3     20        --      --   --   --     A                                          5         5       4    5    5      --                                         1.25      --      --   5    5      --                                   4     5         5       4    5    5      --                                   6     5         5       5    5    5      A                                          1.25      2       3    3    5      --                                   8     20        --      --   --   --     A                                          5         5       5    5    5      --                                         1.25      --      --   5    5      --                                   9     20        --      --   --   --     A                                          5         5       5    5    5      --                                   10    5         5       5    5    5      A                                          1.25      2       2    4    5      --                                   12    20        --      --   --   --     B                                          5         5       4    4    5      --                                   14    5         4       4    4    5      A                                          1.25      2       2    3    5      --                                   16    5         5       4    5    5      --                                         1.25      3       3    5    5      --                                   17    5         5       4    5    5      --                                         1.25      4       3    5    5      --                                   18    20        5       5    5    5      A                                          5         5       5    5    5      A                                          1.25      5       5    5    5      --                                   (a)   5         0       0    1    4                                                 1.25      0       0    0    2      --                                   (b)   5         1       1    2    5      D                                          1.25      0       0    0    3      --                                   (c)   5         0       0    1    4                                           ______________________________________                                    

TEST EXAMPLE 3

Plastic trays (35 cm×25 cm×15 cm) were filled with upland field soil,and the seeds of tall morningglory, velvetleaf, prickly sida,jimsonweed, black nightshade, redroot pigweed, johnsongrass and greenfoxtail, and the seeds of cotton and soybean were sowed therein. Adesigned amount of the test compound formulated into a wettable powderaccording to formulation of Example 1 or 5 and dispersed in water wassprayed over the top by means of a small hand sprayer at a spray volumeof 5 liters per are. After the spraying, the test plants were grown in agreenhouse for 20 days, and phytotoxicity and herbicidal activity wereexamined. The results are shown in Table 10.

                                      TABLE 10                                    __________________________________________________________________________    Dosage                                                                        (weight of                                                                              Herbicidal activity                                                 Com-                                                                              active in-                                                                          Tall               Black             Phyto-                         pound                                                                             gredient,                                                                           morning-                                                                           Velvet-                                                                            Prickly                                                                           Jimson-                                                                            night-                                                                            Redroot                                                                            Johnson-                                                                           Green                                                                             toxicity                       No. g/are)                                                                              glory                                                                              leaf sida                                                                              weed shade                                                                             pigweed                                                                            grass                                                                              foxtail                                                                           Cotton                                                                            Soybean                    __________________________________________________________________________     3  5     5    5    5   5    5   5    5    5   1   --                             2.5   4    5    5   5    5   5    5    5   0   --                         10  5     5    5    5   5    5   5    5    5   1   1                              2.5   4    5    5   5    5   5    4    5   0   0                          (a) 5     0    4    2   0    3   5    0    2   --  0                          (b) 5     2    5    4   3    5   5    2    4   3   2                              2.5   0    4    3   1    4   5    0    2   2   0                          (c) 5     0    5    2   0    4   5    0    2   0   --                         (d) 20    1    0    2   0    4   5    2    5   0   0                          __________________________________________________________________________

TEST EXAMPLE 4

Plastic trays (35 cm×25 cm×15 cm) were filled with upland field soil,and the seeds of corn, wheat, velvetleaf, cocklebur, tall morningglory,common lambsquarters, black nightshade, common chickweed and greenfoxtail were sowed and grown for 2 or 3 weeks in a greenhouse. Every twotrays were placed in a frame (50 cm×100 cm×40 cm) and a designed amountof the test compound was sprayed thereover by means of a small handsprayer. The test plants were further grown for 3 weeks in thegreenhouse and herbicidal activity and phytotoxicity were examined. Theresults are shown in Table II. In this treatment, the test compound wasformulated into an emulsifiable concentrate according to FormulationExample 2 and applied by diluting it in water (25 liters) with theaddition of a spreading agent. At the time of application, the plantswere generally at the 1 to 4 leaf stage and at a height of 1.5 to 20 cm.

                                      TABLE 11                                    __________________________________________________________________________    Dosage                                                                        (weight of       Herbicidal activity                                          Com-                                                                              active in-                                                                          Phyto-          Tall Common                                                                             Black                                                                             Common                                                                             Green                            pound                                                                             gredient,                                                                           toxicity                                                                             Velvet-                                                                            Cock-                                                                             morning-                                                                           lambs-                                                                             night-                                                                            chick-                                                                             fox-                             No. g/are)                                                                              Corn                                                                             Wheat                                                                             leaf lebur                                                                             glory                                                                              quarters                                                                           shade                                                                             weed tail                             __________________________________________________________________________     1  0.63  1  1   5    5   5    5    5   4    3                                    0.32  1  0   5    5   5    5    4   3    2                                14  0.63  -- 1   5    5   5    5    5   4    4                                    0.32  1  1   5    5   5    5    5   2    2                                (e) 2.5   0  --  5    5   5    --   --  --   1                                    1.25  0  --  4    3   3    --   --  --   0                                (f) 2.5   -- 0   --   --  --   5    5   5    0                                    1.25  -- 0   --   --  --   5    4   3    0                                __________________________________________________________________________

TEST EXAMPLE 5

Wagner's pots (1/5000 are) were filled with paddy fielded soil and theseeds of annual weeds (e.g. barnyard-grass, monochoria, broad-leavedweeds) were sowed to 2 to 3 cm depth, and water was poured therein. Thetubers or buds of perennial weeds (e.g. slender spikerush, hardstembulrush, arrowhead) were transplanted therein and grown for 5 days. Atthe time when the germination occurred, a designed amount of the testcompound formulated in an emulsifiable concentrate according toFormulation Example 2 or 6 was applied to the pots by perfusion.Thereafter, the test plants were grown for an additional 4 weeks andherbicidal activity was examined. The results are shown in Table 12.

                                      TABLE 12                                    __________________________________________________________________________    Dosage                                                                        (weight of  Herbicidal activity                                                     active in-         Broad-                                               Compound                                                                            gredient,                                                                           Barnyard-    leaved                                                                            Slender                                                                            Hardstem                                                                           Arrow-                                 No.   g/are)                                                                              grass Monochoria                                                                           weed                                                                              spikerush                                                                          bulrush                                                                            head                                   __________________________________________________________________________     9    0.5   5     5      5   5    5    5                                            0.25  4     5      5   4    4    4                                      14    0.5   5     5      5   5    5    5                                            0.25  4     5      5   4    4    4                                      (a)   0.5   0     3      3   1    1    0                                            0.25  0     1      1   0    0    0                                      (b)   0.5   0     3      3   2    1    0                                            0.25  0     2      1   1    0    0                                      (c)   0.5   0     3      2   1    2    1                                            0.25  0     2      1   0    0    0                                      (g)   0.5   2     2      2   2    1    1                                            0.25  1     2      2   1    0    0                                      __________________________________________________________________________

What is claimed is:
 1. A condensed phenylurazol of the formula:##STR28## wherein X is a chlorine atom or a bromine atom, Y and Z areeach an oxygen atom or a sulfur atom and R is a C₁ -C₃ alkyl group, anallyl group or a propargyl group and n is
 4. 2. The condensedphenylurazol according to claim 1, wherein at least one of Y and Z is anoxygen atom. 3.2-(4-Chloro-2-fluoro-5-methoxyphenyl)-5,6,7,8-tetrahydro-1H-[1,2,4]triazolo[1.2-a]pyridazine-1,3(2H)-dione.4.2-(4-Chloro-2-fluoro-5-methoxyphenyl)-5,6,7,8-tetrahydro-1H-[1,2,4]triazolo[1.2-a]pyridazine-3-thioxo-1(2H)-one.5.2-[4-Chloro-2-fluoro-5-(1-methylethoxy)-phenyl]-5,6,7,8-tetrahydro-1H-[1,2,4]triazolo[1,2-a]-pyridazine-1,3(2H)-dione.6.2-(4-Chloro-2-fluoro-5-propoxyphenyl)-5,6,7,8-tetrahydro-1H-[1,2,4]triazolo[1,2-a]pyridazine-1,3(2H)-dione.7.2-[4-Chloro-2-fluoro-5-(2-propynyloxy)-phenyl]-5,6,7,8-tetrahydro-1H-[1,2,4]triazolo[1,2-a]-pyridazine-1,3(2H)-dione.8. A herbicidal composition which comprises a herbicidally effectiveamount of the condensed phenylurazol according to claim 1 and an inertcarrier.
 9. A method for controlling or exterminating weeds whichcomprises applying a herbicidally effective amount of the condensedphenylurazol according to claim 1 to the area where the weeds grow orwill grow.